Many different processes for the oligomerisation of olefinic compounds are known. The oligomerisation of ethylene and similar processes are described in PCT/ZA2003/000187 which is incorporated herein by reference.
The inventors of the present invention have now found that a tetramerisation reaction as described in PCT/ZA2003/00187 and PCT/ZA2003/000186 (incorporated herein by reference) can be combined with at least one further oligomerisation reaction to yield a mixture of tetramers and other oligomers, wherein the product stream of the tetramerisation reaction contains more than 30% of the tetramer olefin. The processes described in PCT/ZA2003/000187 and PCT/ZA2003/000186 also yield a somewhat mixed oligomerised product, the ratios between the oligomers being dependent on and determined by the catalyst system and reaction conditions selected. The current process can now be used to manipulate the ratios of the oligomers in the product stream as may be required by market needs.
Most surprisingly it has been found that a tetramerisation reaction as described in this patent application is compatible with a further oligomerisation reaction and accordingly is suitable to manipulate the composition of the oligomerised product stream.